---

uidlist.c

Go to the documentation of this file.

/* 
   Copyright (C) Andrew Tridgell 1996
   Copyright (C) Paul Mackerras 1996
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* handle the mapping of uid/gid and user/group names between systems.
   If the source username/group does not exist on the target then use
   the numeric ids. Never do any mapping for uid=0 or gid=0 as these
   are special.
*/

#include "rsync.h"

extern int preserve_uid;
extern int preserve_gid;
extern int numeric_ids;
extern int am_root;

struct idlist {
        struct idlist *next;
        int id, id2;
        char *name;
};

static struct idlist *uidlist;
static struct idlist *gidlist;

static struct idlist *add_list(int id, char *name)
{
        struct idlist *list = (struct idlist *)malloc(sizeof(list[0]));
        if (!list) out_of_memory("add_list");
        list->next = NULL;
        list->name = strdup(name);
        if (!list->name) out_of_memory("add_list");
        list->id = (int)id;
        return list;
}



/* turn a uid into a user name */
static char *uid_to_name(uid_t uid)
{
        struct passwd *pass = getpwuid(uid);
        if (pass) return(pass->pw_name);
        return NULL;
}

/* turn a gid into a group name */
static char *gid_to_name(gid_t gid)
{
        struct group *grp = getgrgid(gid);
        if (grp) return(grp->gr_name);
        return NULL;
}

static int map_uid(int id, char *name)
{
        uid_t uid;
        if (name_to_uid(name, &uid) && uid != 0)
                return uid;
        return id;
}

static int map_gid(int id, char *name)
{
        gid_t gid;
        if (name_to_gid(name, &gid) && gid != 0)
                return gid;
        return id;
}

/* this function is a definate candidate for a faster algorithm */
static uid_t match_uid(uid_t uid)
{
        static uid_t last_in, last_out;
        struct idlist *list = uidlist;

        if (uid == last_in) return last_out;

        last_in = uid;

        while (list) {
                if (list->id == (int)uid) {
                        last_out = (uid_t)list->id2;
                        return last_out;
                }
                list = list->next;
        }
        
        last_out = uid;
        return last_out;
}

static gid_t match_gid(gid_t gid)
{
        static gid_t last_in, last_out;
        struct idlist *list = gidlist;

        if (gid == last_in) return last_out;

        last_in = gid;

        while (list) {
                if (list->id == (int)gid) {
                        last_out = (gid_t)list->id2;
                        return last_out;
                }
                list = list->next;
        }
        
        if (am_root)
                last_out = gid;
        else
                last_out = (gid_t) -1;
        return last_out;
}

/* add a uid to the list of uids */
void add_uid(uid_t uid)
{
        struct idlist *list = uidlist;
        char *name;

        if (numeric_ids) return;

        /* don't map root */
        if (uid==0) return;

        if (!list) {
                if (!(name = uid_to_name(uid))) return;
                uidlist = add_list((int)uid, name);
                return;
        }

        while (list->next) {
                if (list->id == (int)uid) return;
                list = list->next;
        }

        if (list->id == (int)uid) return;

        if (!(name = uid_to_name(uid))) return;

        list->next = add_list((int)uid, name);
}

/* add a gid to the list of gids */
void add_gid(gid_t gid)
{
        struct idlist *list = gidlist;
        char *name;

        if (numeric_ids) return;

        /* don't map root */
        if (gid==0) return;

        if (!list) {
                if (!(name = gid_to_name(gid))) return;
                gidlist = add_list((int)gid, name);
                return;
        }

        while (list->next) {
                if (list->id == (int)gid) return;
                list = list->next;
        }

        if (list->id == (int)gid) return;

        if (!(name = gid_to_name(gid))) return;

        list->next = add_list((int)gid, name);
}


/* send a complete uid/gid mapping to the peer */
void send_uid_list(int f)
{
        struct idlist *list;

        if (numeric_ids) return;

        if (preserve_uid) {
                /* we send sequences of uid/byte-length/name */
                list = uidlist;
                while (list) {
                        int len = strlen(list->name);
                        write_int(f, list->id);
                        write_byte(f, len);
                        write_buf(f, list->name, len);
                        list = list->next;
                }

                /* terminate the uid list with a 0 uid. We explicitly exclude
                   0 from the list */
                write_int(f, 0);
        }

        if (preserve_gid) {
                list = gidlist;
                while (list) {
                        int len = strlen(list->name);
                        write_int(f, list->id);
                        write_byte(f, len);
                        write_buf(f, list->name, len);
                        list = list->next;
                }
                write_int(f, 0);
        }
}

/* recv a complete uid/gid mapping from the peer and map the uid/gid
   in the file list to local names */
void recv_uid_list(int f, struct file_list *flist)
{
        int id, i;
        char *name;
        struct idlist *list;

        if (numeric_ids) return;

        if (preserve_uid) {
                /* read the uid list */
                list = uidlist;
                id = read_int(f);
                while (id != 0) {
                        int len = read_byte(f);
                        name = (char *)malloc(len+1);
                        if (!name) out_of_memory("recv_uid_list");
                        read_sbuf(f, name, len);
                        if (!list) {
                                uidlist = add_list(id, name);
                                list = uidlist;
                        } else {
                                list->next = add_list(id, name);
                                list = list->next;
                        }
                        list->id2 = map_uid(id, name);
                        free(name);
                        id = read_int(f);
                }
        }


        if (preserve_gid) {
                /* and the gid list */
                list = gidlist;
                id = read_int(f);
                while (id != 0) {
                        int len = read_byte(f);
                        name = (char *)malloc(len+1);
                        if (!name) out_of_memory("recv_uid_list");
                        read_sbuf(f, name, len);
                        if (!list) {
                                gidlist = add_list(id, name);
                                list = gidlist;
                        } else {
                                list->next = add_list(id, name);
                                list = list->next;
                        }
                        list->id2 = map_gid(id, name);
                        free(name);
                        id = read_int(f);
                }
        }

        if (!(am_root && preserve_uid) && !preserve_gid) return;

        /* now convert the uid/gid of all files in the list to the mapped
           uid/gid */
        for (i=0;i<flist->count;i++) {
                if (am_root && preserve_uid && flist->files[i]->uid != 0) {
                        flist->files[i]->uid = match_uid(flist->files[i]->uid);
                }
                if (preserve_gid && flist->files[i]->gid != 0) {
                        flist->files[i]->gid = match_gid(flist->files[i]->gid);
                }
        }
}

---